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Dear all,
Maybe somebody can explain to me is it possible to distinguish
whether unchanged drug in feces origins from unabsorbed part from tablet
or from bile excretion. Can time of appearance in feces play a role
in separating this to unchanged fractions of drug. I Know that
gastric emptying is variable and that transit time in small intestine
is not but I do not know whether transit time in large bowel is
variable parameter?
If this time of appearance in feces is not something I can use in
separating this two fractions what would be right method?
Thx in advance,
Lidija
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Dear Lidija:
It would be really hard to distinguish whether the drug in feces is
from unabsorbed fraction or biliary excretion, since the feces takes
some time to form and excrete. The time it forms also varies.
Therefore, the time of appearance in feces is not a practical
measurement.
The right method might be to collect bile from the animal, or have
bile duct completely ligated and do a comparison study.
In addition, if there is strong biliary excretion, you might see 2nd
peak in plasma PK.
D.
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The following message was posted to: PharmPK
Dear Lidija
It is possible to perform a study on isolated perfused rat liver and to
collect the bile and analyse it in order to establish the ration
between the
metabolite and the parent drug. Then when the ratio will be obtain it
will
be easy for you to compare the unchanged form of the drug in feces
with the
theoretical bile mediated ratio.
I hope it helps.
Regards
Francoise BREE
Xenoblis
Parc d'Affaires de la Breteche
35760 Saint Gregoire FRANCE
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The following message was posted to: PharmPK
A simpler way to get an indication of biliary excretion if bile
cannulation is not possible, may be to look in faeces after i.v.
Dosing...
Ylva
--
Ylva Terelius
Medivir AB
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Copyright 1995-2007 David W. A. Bourne (david@boomer.org)